Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 55-56). Also available on the Internet.

Overuse of the Interstate and National Highway Systems has led many urban freeways to suffer from recurrent congestion and high crash rates. One method of ameliorating these problems is through the use of Active Traffic Management (ATM). Within ATM, the practice of speed harmonization is well suited to improving safety and reducing delay. In this study, speed harmonization is applied to a segment of Interstate Highway 35, just south of downtown Austin, Texas. First, the need for congestion and safety improvements will be established. Then, the framework of a speed harmonization system will be developed through a synthesis of speed harmonization best practice. Next, the speed harmonization framework will be evaluated for its impact on efficiency through the development of before and after micro-simulation models. Finally, the trajectory files generated from simulation will be analyzed using surrogate safety measures to assess the safety impact of the proposed speed harmonization system. / text

Variable speed drive technology has advanced dramatically in the last 10 years with the advent of new power devices. In this study, a three phase induction motor drive using Insulated Gate Bipolar Transistors (IGBT) at the inverter power stage is introduced to implement speed and position control for the revolving stage in the Frederic Wood Theatre This thesis presents a solution to control a 3-phase induction motor using the Texas Instruments (TI) Digital Signal Processor (DSP) TMS320F2407A. The use of this DSP yields enhanced operations, fewer system components, lower system cost and increased efficiency. The control algorithm is based on the constant volts-per-hertz principle because the exact speed control is not needed. Reflective object sensors which are mounted on concrete frame are used to detect accurate edge position of revolving stage. The sinusoidal voltage waveforms are generated by the DSP using the space vector modulation technique. In order to satisfy some operating conditions for safe and agreeable operation, a look-up table, which is used to give command voltage and speed signals in software, is applied to limit the maximum speed and acceleration of the revolving stage. Meanwhile, a boost voltage signal is added at the low frequency areas to make the motor produce maximum output torque when starting. A test prototype is then built to validate the performance. Several tests are implemented into the IGBT drive to explore the reason for unacceptable oscillations in IGBT’s gate control signals. Improvement methods in hardware layout are suggested for the final design.

This thesis describes work that has been carried out to develop a scaled down laboratory test bed for use in the optimisation of fan driven air ventilation systems found at the various Anglo Coal South African mines. The present system involved in the movement of air underground comprises a fixed speed centrifugal fan driven damper controlled system. National Power Contractors (NPC) together with the University of KwaZulu-Natal (UKZN) proposed a variable speed automated controlled system, but the costs of installing Variable Speed Drives (VSD) and their impact on the energy consumption of a system prior to being installed are important. In addition deliverables required by the industrial partner NPC was to develop a calibrated simulation model where any fan system could be simulated showing potential energy savings. A test bed was therefore constructed to evaluate the power usage of a VSD while driving a simulated fan. The test bed comprised of two Field Oriented Controlled induction machines. A ventilation system at Anglo Coal’s Vlaklaagte colliery was proposed to be simulated by the test bed to develop the Measurement and Verification (M&V) methodology required to represent a business case, but since data from this fan system was not available two other fan systems were studied. One fan system was built at the UKZN whilst the other industrial fan system was at Anglo Coal’s Greenside colliery. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 3, 2008) Vita. Includes bibliographical references.

Variable speed drive technology has advanced dramatically in the last 10 years with the advent of new power devices. In this study, a three phase induction motor drive using Insulated Gate Bipolar Transistors (IGBT) at the inverter power stage is introduced to implement speed and position control for the revolving stage in the Frederic Wood Theatre This thesis presents a solution to control a 3-phase induction motor using the Texas Instruments (TI) Digital Signal Processor (DSP) TMS320F2407A. The use of this DSP yields enhanced operations, fewer system components, lower system cost and increased efficiency. The control algorithm is based on the constant volts-per-hertz principle because the exact speed control is not needed. Reflective object sensors which are mounted on concrete frame are used to detect accurate edge position of revolving stage. The sinusoidal voltage waveforms are generated by the DSP using the space vector modulation technique. In order to satisfy some operating conditions for safe and agreeable operation, a look-up table, which is used to give command voltage and speed signals in software, is applied to limit the maximum speed and acceleration of the revolving stage. Meanwhile, a boost voltage signal is added at the low frequency areas to make the motor produce maximum output torque when starting. A test prototype is then built to validate the performance. Several tests are implemented into the IGBT drive to explore the reason for unacceptable oscillations in IGBT’s gate control signals. Improvement methods in hardware layout are suggested for the final design. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No description available.

Demand for energy-saving variable speed drives in low-cost, high-volume appliances has increased due to energy and environmental concerns and hence the need to comply with new regulations. Switched reluctance motor (SRMs) have been considered by many as attractive alternatives for brush commutated motors or permanent magnet brushless dc motors (PMBDCMs) in such cost-sensitive applications. The SRMs' unique features such as simple and fault-tolerant structure and unidirectional flow of their phase currents endow them with the possibility of various configurations on both machine and converter topologies for different applications. In the present study, three different variable-speed motor drive systems are proposed, studied, and implemented for their deployment in low-cost, high-volume applications with the power rating of 1.5kW or less. Two different two-phase SRMs and three different power converters are employed to realize three different low-cost drive systems. The first drive system is realized using a novel converter requiring only a single-controllable switch and an asymmetric two-phase 8/4 SRM capable of self-starting and four-quadrant operation. The second drive system is realized using another novel converter requiring two controllable switches, that way to achieve better control and utilization of the asymmetric 8/4 motor. The target applications for both drive systems are low power, low performance drives such as fans, hand tools, small appliances, etc. The third system is realized using a high-speed two-phase 4/2 SRM and a split ac source converter, which is designed for high-speed applications such as vacuum cleaners, ultracentrifuges, etc. The control and design aspects for each drive system are studied. Selection of optimal firing angles and optimal number of winding turns are also investigated. All of the drive systems are first demonstrated on the position sensor-based speed-control scheme. To make the drive system even more cost-competitive, operation without the position sensor using the novel parameter insensitive sensorless control scheme is proposed and implemented. Concept, analysis, simulation, and experimental verification of the proposed sensorless scheme are discussed in detail. / Ph. D.

Variable speed limits (VSL) are dynamic traffic management systems designed to increase the efficiency and safety of highways. While the macroscopic performance of VSL systems is well explored in the existing literature, there is a need to further understand the microscopic behavior of vehicles driving in VSL zones. Specifically, driver compliance to advisory VSL systems is quantified based on a driving-simulation experiment and introduced into a broader microscopic behavior model. Statistical analysis indicates that VSL compliance can be predicted based upon several VSL design parameters. The developed two-state microscopic model is calibrated to driving-simulation trajectory data. A calibrated VSL microscopic model can be utilized for new VSL control and macroscopic performance studies, adding an increased dimension of realism to simulation work. As an example, the microscopic model is implemented within VISSIM (overriding the default car-following model) and utilized for a safety-mobility performance assessment of an incident-responsive VSL control algorithm implemented in a MATLAB COM interface. Examination of the multi-objective optimization frontier reveals an inverse relationship between safety and mobility under different control algorithm parameters. Engineers are thus faced with a decision between performing multi-objective optimization and selecting a dominant VSL control objective (e.g. maximizing safety versus mobility performance). / Master of Science